Nutrient uptake plasticity in phytoplankton sustains future ocean net primary production

Abstract

Annually, marine phytoplankton convert approximately 50 billion tons of dissolved inorganic carbon to particulate and dissolved organic carbon, a portion of which is exported to depth via the biological carbon pump. Despite its important roles in regulating atmospheric carbon dioxide via carbon sequestration and in sustaining marine ecosystems, model-projected future changes in marine net primary production are highly uncertain even in the sign of the change. Here, using an Earth system model, we show that frugal utilization of phosphorus by phytoplankton under phosphate-stressed conditions can overcompensate the previously projected 21st century declines due to ocean warming and enhanced stratification. Our results, which are supported by observations from the Hawaii Ocean Time-series program, suggest that nutrient uptake plasticity in the subtropical ocean plays a key role in sustaining phytoplankton productivity and carbon export production in a warmer world.

Effects of phytoplankton physiology on global ocean biogeochemistry and climate

“…Surface PO43− concentration has been used as an indicator for atmospheric pCO 2 because the utilization of surface PO43− is associated with C fixation ( 38 – 40 ). This relation becomes more complicated when considering a variable pP:C, which may amplify ( 38 , 41 ) or damp ( 23 ) the effect of surface PO43− changes on atmospheric pCO 2 . In the present study, the correlation between pCO 2 and surface PO43− depends on whether we are looking at variable Q0,phyN or Q0,phyP.…”

“…The effects of variable phytoplankton C:N:P on the global biogeochemistry have received considerable attention in recent years. Variable C:N:P affects surface nutrient distributions and inventories (10,(17)(18)(19) and could also mitigate the changes in C export under different climate conditions (20)(21)(22)(23). Previous studies have considered how variations in elemental stoichiometry may be linked to the diversity of phytoplankton functional types (10,24) and how allowing for variable stoichiometry affects future climate projections (25).…”

Biodiversity and Stoichiometric Plasticity Increase Pico‐Phytoplankton Contributions to Marine Net Primary Productivity and the Biological Pump

“…Does representation of variable carbon to nutrient stoichiometry within OBGC models potentially buffer the well‐documented positive ocean carbon cycle feedback to future climate warming? A number of ESM's that have included representation of variable carbon to phosphorus stoichiometry within the ocean ecosystem component generally predict a more resilient response for future marine NPP and carbon export fluxes, with modest ∼0 – <5% declines by year 2100 (Buchanan et al., 2018; Kwiatkowski et al., 2018; Kwon et al., 2022; Matsumoto et al., 2020; Tanioka & Matsumoto, 2017). The inclusion of variable phosphorus to carbon stoichiometry within the marine ecosystem component permits flexibility in phytoplankton phosphorus quotas.…”

Elemental stoichiometry of the key calcifying marine phytoplankton Emiliania huxleyi under ocean climate change: A meta‐analysis

“…Several newer‐generation models now incorporate some level of variable phytoplankton stoichiometry (typically variable C:P while C:N remains fixed, e.g. Galbraith et al, 2015; Hayashida et al, 2019; Kwon et al, 2022; Séférian et al, 2020). The implementation of variable stoichiometry tends to improve model representation of observed regional patterns in particulate C:N:P (Inomura et al, 2022; Kwon et al, 2022; Moreno et al, 2018) and modelled patterns and trends in net primary productivity tend to better match the contributions of phytoplankton to global carbon fluxes expected from observational data (Galbraith & Martiny, 2015; Kwiatkowski et al, 2018).…”

“…Galbraith et al, 2015; Hayashida et al, 2019; Kwon et al, 2022; Séférian et al, 2020). The implementation of variable stoichiometry tends to improve model representation of observed regional patterns in particulate C:N:P (Inomura et al, 2022; Kwon et al, 2022; Moreno et al, 2018) and modelled patterns and trends in net primary productivity tend to better match the contributions of phytoplankton to global carbon fluxes expected from observational data (Galbraith & Martiny, 2015; Kwiatkowski et al, 2018). However, the ultimate influence of variable phytoplankton C:N:P on marine net primary productivity, export productivity or oceanic CO 2 uptake remains uncertain (Kwon et al, 2022).…”